package en.edu.scau.cmi.zhanzhiyong.carpter09;

public class EncryptAndDecrypt {
	
	String encrypt(String sourceString, String password) {
		char[] p = password.toCharArray();
		int n = p.length;
		
		char[] c = sourceString.toCharArray();
		int m = c.length;
		
		for(int k = 0;k < m;k++) {
			int mima = c[k] + p[k%n];
			c[k] = (char)mima;
		}
		
		return new String(c);
	}
	
	String decrypt(String sourceString, String password) {
		char[] p = password.toCharArray();
		int n = p.length;
		
		char[] c = sourceString.toCharArray();
		int m = c.length;
		
		for(int k = 0;k < m;k++) {
			int mima = c[k] - p[k%n];
			c[k] = (char)mima;
		}
		
		return new String(c);
	}
}
